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-------------------------------------------------------------------------------- ---- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS ---- ---- S Y S T E M . T A S K I N G . I N I T I A L I Z A T I O N ---- ---- S p e c ---- ---- $Revision: 1.22 $-- ---- Copyright (C) 1992-1999, Free Software Foundation, Inc. ---- ---- GNARL is free software; you can redistribute it and/or modify it under ---- terms of the GNU General Public License as published by the Free Soft- ---- ware Foundation; either version 2, or (at your option) any later ver- ---- sion. GNARL is distributed in the hope that it will be useful, but WITH- ---- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY ---- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License ---- for more details. You should have received a copy of the GNU General ---- Public License distributed with GNARL; see file COPYING. If not, write ---- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, ---- MA 02111-1307, USA. ---- ---- As a special exception, if other files instantiate generics from this ---- unit, or you link this unit with other files to produce an executable, ---- this unit does not by itself cause the resulting executable to be ---- covered by the GNU General Public License. This exception does not ---- however invalidate any other reasons why the executable file might be ---- covered by the GNU Public License. ---- ---- GNARL was developed by the GNARL team at Florida State University. It is ---- now maintained by Ada Core Technologies Inc. in cooperation with Florida ---- State University (http://www.gnat.com). ---- ---------------------------------------------------------------------------------- This package provides overall initialization of the tasking portion of the-- RTS. This package must be elaborated before any tasking features are used.-- It also contains initialization for Ada Task Control Block (ATCB) records.withAda.Exceptions;
-- used for Exception_Occurrence_AccesspackageSystem.Tasking.InitializationisprocedureRemove_From_All_Tasks_List (T : Task_ID);
-- Remove T from All_Tasks_List.-------------------------------------------------- Static (Compile-Time) Configuration Flags ---------------------------------------------------- ?????-- Maybe this does not belong here? Where else?-- For now, it is here because so is Change_Base_Priority,-- and the two are used together.
Dynamic_Priority_Support : constant Boolean := True;
-- Should we poll for pending base priority changes at every-- abort completion point?----------------------------------- Tasking-Specific Soft Links ------------------------------------- These permit us to leave out certain portions of the tasking-- run-time system if they are not used. They are only used internally-- by the tasking run-time system.-- So far, the only example is support for Ada.Task_Attributes.typeProc_Tisaccessprocedure (T : Task_ID);
procedureFinalize_Attributes (T : Task_ID);
procedureInitialize_Attributes (T : Task_ID);
Finalize_Attributes_Link : Proc_T := Finalize_Attributes'Access;
-- should be called with abortion deferred and T.L write-locked
Initialize_Attributes_Link : Proc_T := Initialize_Attributes'Access;
-- should be called with abortion deferred, but holding no locks--------------------------- Abort Defer/Undefer ----------------------------- Defer_Abort defers the affects of low-level abort and priority change-- in the calling task until a matching Undefer_Abort call is executed.-- Undefer_Abort DOES MORE than just undo the effects of one call to-- Defer_Abort. It is the universal "polling point" for deferred-- processing, including the following:-- 1) base priority changes-- 2) exceptions that need to be raised-- 3) abort/ATC-- Abort deferral MAY be nested (Self_ID.Deferral_Level is a count),-- but to avoid waste and undetected errors, it generally SHOULD NOT-- be nested. The symptom of over-deferring abort is that an exception-- may fail to be raised, or an abort may fail to take place.-- Therefore, there are two sets of the inlinable defer/undefer-- routines, which are the ones to be used inside GNARL.-- One set allows nesting. The other does not. People who-- maintain the GNARL should try to avoid using the nested versions,-- or at least look very critically at the places where they are-- used.-- In general, any GNARL call that is potentially blocking, or-- whose semantics require that it sometimes raise an exception,-- or that is required to be an abort completion point, must be-- made with abort Deferral_Level = 1.-- In general, non-blocking GNARL calls, which may be made from inside-- a protected action, are likely to need to allow nested abort-- deferral.-- With some critical exceptions (which are supposed to be documented),-- internal calls to the tasking runtime system assume abort is already-- deferred, and do not modify the deferral level.-- There is also a set of non-linable defer/undefer routines,-- for direct call from the compiler. These are not in-lineable-- because they may need to be called via pointers ("soft links").-- For the sake of efficiency, the version with Self_ID as parameter-- should used wherever possible. These are all nestable.-- Non-nestable inline versions --procedureDefer_Abort (Self_ID : Task_ID);
pragma Inline (Defer_Abort);
procedureUndefer_Abort (Self_ID : Task_ID);
pragma Inline (Undefer_Abort);
-- Nestable inline versions --procedureDefer_Abort_Nestable (Self_ID : Task_ID);
pragma Inline (Defer_Abort_Nestable);
procedureUndefer_Abort_Nestable (Self_ID : Task_ID);
pragma Inline (Undefer_Abort_Nestable);
-- NON-INLINE versions without Self_ID for code generated by the-- expander and for hard linksprocedureDefer_Abortion;
procedureUndefer_Abortion;
-- ?????-- Try to phase out all uses of the above versions.functionCheck_Abort_Statusreturn Integer;
-- Returns Boolean'Pos (True) iff abort signal should raise-- Standard.Abort_Signal. Only used by IRIX currently.----------------------------- Change Base Priority -----------------------------procedureChange_Base_Priority (T : Task_ID);
-- Change the base priority of T.-- Has to be called with the affected task's ATCB write-locked.-- May temporariliy release the lock.procedurePoll_Base_Priority_Change (Self_ID : Task_ID);
-- Has to be called with Self_ID's ATCB write-locked.-- May temporariliy release the lock.pragma Inline (Poll_Base_Priority_Change);
------------------------ Task Lock/Unlock ------------------------procedureTask_Lock (Self_ID : Task_ID);
procedureTask_Unlock (Self_ID : Task_ID);
-- These are versions of Lock_Task and Unlock_Task created for use-- within the GNARL.procedureFinal_Task_Unlock (Self_ID : Task_ID);
-- This version is only for use in Terminate_Task, when the task-- is relinquishing further rights to its own ATCB.-- There is a very interesting potential race condition there, where-- the old task may run concurrently with a new task that is allocated-- the old tasks (now reused) ATCB. The critical thing here is to-- not make any reference to the ATCB after the lock is released.-- See also comments on Terminate_Task and Unlock.procedureWakeup_Entry_Caller
(Self_ID : Task_ID;
Entry_Call : Entry_Call_Link;
New_State : Entry_Call_State);
pragma Inline (Wakeup_Entry_Caller);
-- This is called at the end of service of an entry call,-- to abort the caller if he is in an abortable part, and-- to wake up the caller if he is on Entry_Caller_Sleep.-- Call it holding the lock of Entry_Call.Self.---- Timed_Call or Simple_Call:-- The caller is waiting on Entry_Caller_Sleep, in-- Wait_For_Completion, or Wait_For_Completion_With_Timeout.---- Conditional_Call:-- The caller might be in Wait_For_Completion,-- waiting for a rendezvous (possibly requeued without abort)-- to complete.---- Asynchronous_Call:-- The caller may be executing in the abortable part o-- an async. select, or on a time delay,-- if Entry_Call.State >= Was_Abortable.procedureLocked_Abort_To_Level
(Self_ID : Task_ID;
T : Task_ID;
L : ATC_Level);
pragma Inline (Locked_Abort_To_Level);
-- Abort a task to a specified ATC level.-- Call this only with T locked.end System.Tasking.Initialization;